Relative reactivities of primary alcohols as substrates of liver alcohol dehydrogenase

1968 ◽  
Vol 46 (4) ◽  
pp. 381-385 ◽  
Author(s):  
C. S. Tsai
Keyword(s):  
Alcohol Dehydrogenase ◽  
Rate Equation ◽  
Electronic Effect ◽  
Graphical Analysis ◽  
Primary Alcohols ◽  
Structural Requirement ◽  
Liver Alcohol Dehydrogenase ◽  
Polar Groups ◽  
Kinetic Coefficients ◽  
Kinetics Of

To obtain information concerning the general structural requirement of alcohols as substrates of liver alcohol dehydrogenase, the kinetics of the enzymic oxidation of primary alcohols were studied. All the active substrates possess hydrophobic side groups. Introduction of polar groups renders alcohols inactive or inhibitory. To correlate reactivities of primary alcohols as substrates with the nature of their side groups, their relative reactivities are expressed in terms of kinetic coefficients which were solved from the rate equation by successive graphical analysis. Based on kinetic results, the relative reactivities of primary alcohols as substrates of liver alcohol dehydrogenase are discussed in relation to the hydrophobic interaction and the electronic effect of their side groups.

scholarly journals Thermodynamics and Molecular Kinetics of Liver Alcohol Dehydrogenase.

1963 ◽  
Vol 17 supl. ◽  
pp. 27-33 ◽  
Author(s):  
Keith Dalziel ◽  
Gad Yagil ◽  
Warren F. Diven ◽  
Mark Takahashi
Keyword(s):  
Alcohol Dehydrogenase ◽  
Liver Alcohol Dehydrogenase ◽  
Kinetics Of

scholarly journals Kinetics and reaction mechanism of yeast alcohol dehydrogenase with long-chain primary alcohols

1976 ◽  
Vol 157 (1) ◽  
pp. 15-22 ◽  
Author(s):  
W Schöpp ◽  
H Aurich
Keyword(s):  
Alcohol Dehydrogenase ◽  
Dissociation Constants ◽  
Kinetic Studies ◽  
Random Order ◽  
Primary Alcohols ◽  
Yeast Alcohol Dehydrogenase ◽  
Kinetic Coefficients ◽  
Non Linear ◽  
High Concentrations ◽  
Long Chain

Kinetic studies of yeast alcohol dehydrogenase with NAD+ and ethanol, hexanol or decanol as substrates invariably result in non-linear Lineweaver-Burk plots if the alcohol is the variable substrate. The kinetic coefficients determined from secondary plots are consistent with an ‘equilibrium random-order‘ mechanism for extremely low alcohol concentrations and for all alcohols, the transformation of the ternary complexes being the rate-limiting step of the reaction. This mechanism also applies to long-chain substrates at high concentrations, whereas the rate of the ethanol-NAD+ reaction at high ethanol concentrations is determined by the dissociation of the enzyme-NADH complex. The dissociation constants for the enzyme-NAD+ complex and for the enzyme-alcohol complexes obtained from the kinetic quotients satisfactorily correspond to the dissociation constants obtained by use of other techniques. It is suggested that the non-linear curves may be attributed to a structural change in the enzyme itself, caused by the alcohol.

scholarly journals Kinetic and mechanistic studies of methylated liver alcohol dehydrogenase

1978 ◽  
Vol 173 (2) ◽  
pp. 483-496 ◽  
Author(s):  
C S Tsai
Keyword(s):  
Alcohol Dehydrogenase ◽  
Substrate Inhibition ◽  
Kinetic Studies ◽  
Primary Alcohols ◽  
Reductive Methylation ◽  
Factors Affecting ◽  
Liver Alcohol Dehydrogenase ◽  
Wide Range ◽  
Lysine Residues ◽  
Michaelis Constants

Reductive methylation of lysine residues activates liver alcohol dehydrogenase in the oxidation of primary alcohols, but decreases the activity of the enzyme towards secondary alcohols. The modification also desensitizes the dehydrogenase to substrate inhibition at high alcohol concentrations. Steady-state kinetic studies of methylated liver alcohol dehydrogenase over a wide range of alcohol concentrations suggest that alcohol oxidation proceeds via a random addition of coenzyme and substrate with a pathway for the formation of the productive enzyme-NADH-alcohol complex. To facilitate the analyses of the effects of methylation on liver alcohol dehydrogenase and factors affecting them, new operational kinetic parameters to describe the results at high substrate concentration were introduced. The changes in the dehydrogenase activity on alkylation were found to be associated with changes in the maximum velocities that are affected by the hydrophobicity of alkyl groups introduced at lysine residues. The desensitization of alkylated liver alcohol dehydrogenase to substrate inhibition is identified with a decrease in inhibitory Michaelis constants for alcohols and this is favoured by the steric effects of substituents at the lysine residues.

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